title: Conversion from selective to comprehensive neck dissection: is it necessary for occult nodal metastasis? 5-year observational study.
abstract: OBJECTIVE
  To compare the therapeutic results between selective neck dissection (SND) and conversion modified radical neck dissection (MRND) for the occult nodal metastasis cases in head and neck squamous cell carcinoma.
  
  
  METHODS
  Forty-four cases with occult nodal metastasis were enrolled in this observational cohort study. For twenty-nine cases, SNDs were done and for fifteen cases, as metastatic nodes were found in the operative field, conversion from selective to MRNDs type II were done. Baseline data on primary site, T and N stage, extent of SND, extracapsular spread of occult metastatic node and type of postoperative adjuvant therapy were obtained. We compared locoregional control rate, overall survival rate and disease specific survival rate between two groups.
  
  
  RESULTS
  Among the 29 patients who underwent SND, only one patient had a nodal recurrence which occurred in the contralateral undissected neck. On the other hand, among the 15 patients who underwent conversion MRND, two patients had nodal recurrences which occurred in previously undissected neck. According to the Kaplan Meier survival curve, there was no statistically significant difference for locoregional control rate, overall survival rate and disease specific survival rate between two groups (P=0.2719, P=0.7596, and P=0.2405, respectively).
  
  
  CONCLUSIONS
  SND is enough to treat occult nodal metastasis in head and neck squamous cell carcinoma and it is not necessary to convert from SND to comprehensive neck dissection.
authors.affiliation: Department of Otorhinolaryngology-Head and Neck Surgery, Ilsong Memorial Institute of Head and Neck Cancer, Hallym University Medical Center, Seoul, Korea.
authors.forename: Sun Min
authors.initials: SM
authors.lastname: Park
authors.forename: Dong Jin
authors.initials: DJ
authors.lastname: Lee
authors.forename: Eun Jae
authors.initials: EJ
authors.lastname: Chung
authors.forename: Jin Hwan
authors.initials: JH
authors.lastname: Kim
authors.forename: Il Seok
authors.initials: IS
authors.lastname: Park
authors.forename: Min Joo
authors.initials: MJ
authors.lastname: Lee
authors.forename: Young Soo
authors.initials: YS
authors.lastname: Rho
keywords: Conversion modified radical neck dissection; Occult nodal metastasis; Selective neck dissection